What is fact vs opinion?

A fact is something that can be demonstrably proven and is held to be true (fire burns). Opinion is a belief that can be based on either fact, speculation, or faith (J.R. "Bob" Dobbs will rescue Subgenii from the Pinks on X-Day).

In a philosophical sense, all facts could be considered opinions if one chooses to argue the point, but most people will say you're simply holding an opinion about a fact.